Modbus Poll test function:

The purpose of this test dialog is to help MODBUS slave device developers to test the device with any string of their own composition.
The list box displays the transmitted data as well as the received data.
You can have several test strings in the pull down list box. When you have entered a string then press the "Add to List" button then the string is added to the list.
The selected string is sent when the "Send" button is pressed.
With the "Save list" button you can store the strings in a text file.

Check the "Add Check" check box if you want to add a CRC or LRC to the end of the input string.

When using the test center you may want to disable communication from other windows. Check the "Read/Write disable" check box in "Read/Write Definition" dialog (F8). Menu->Setup->Read/Write Definition.